Downy mildew: is resistance linked to inoculum concentration?

Leaves of different Vitis vinifera cultivars, susceptible (‘Chasselas’ and ‘2185’), less susceptible (‘2142’) or resistant to downy mildew ('Solaris’ and ‘2091’), were inoculated with four different concentrations of an aqueous sporangia suspension of Plasmopara viticola (5 × 105, 2 × 105, 6 × 104 and 2 × 104 sporangia·ml-1). The infection rate of these samples was then examined by light microscopy and synthesis of stilbenes was analysed at infection sites. Infection rate increased parallel with inoculum concentration, but there was no correlation between the infection rate and resistance to P. viticola. Moreover, at the lowest inoculum concentration, the infection rate is similar for susceptible and resistant grapevine varieties. Quantification of stilbenes at 72 hpi showed that at the lowest inoculum concentration, the most susceptible grape variety synthesized the largest amount of stilbenes, whose level remained however below the ED50 values defined for each of them. Conversely, at the highest inoculum concentration, the most resistant varieties produced the highest amounts of the most toxic stilbenes against P. viticola. The critical role of the inoculum concentration used for artificial inoculation to evaluate grapevine resistance to downy mildew is discussed.

« C’est normal qu’on mollisse ou qu’on vieillisse » : faut-il aborder le déclin fonctionnel avec les personnes âgées en médecine de famille ?

Pour répondre au vieillissement de la population, des initiatives de dépistage et de prise en charge des problèmes de santé liés à l’âge sont mises en place, notamment en médecine de famille. Les résultats préliminaires d’une étude qualitative suggèrent que les personnes âgées sont ambivalentes face à la notion d’anticipation des problèmes, tendent à les banaliser et à être réticentes à en parler spontanément à leur médecin. Cependant, elles trouvent pertinent que ce dernier aborde le sujet avec des questions spécifiques, ceci permettant d’initier une discussion sur des problématiques sensibles. Les possibilités de prise en charge des syndromes gériatriques et du déclin fonctionnel semblent peu connues des patient-e-s. Le dépistage permet donc d’aborder ces problématiques et d’informer les patient-e-s au sujet de solutions existantes. [Among the health strategies to respond to the aging of the population, initiatives for the screening and management of age-related health issues are implemented, including in family medicine. Preliminary results of a qualitative study suggest that elderly people are ambivalent about anticipating age-related issues, tend to trivialize them and to be reluctant to discuss them spontaneously with their doctors. However, they find relevant that their family doctor brings up the topic with specific questions, because that allows initiating a discussion about some of these sensitive issue. It appears that the awareness of the existing management of geriatric syndromes and functional decline possibilities is rather low. A screening initiative is therefore an opportunity to address these different issues and to inform patients about existing solutions.]]]> fre oai:serval.unil.ch:BIB_7917561D1F2C 2022-05-07T01:20:55Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_7917561D1F2C Good and Bad Days: Fluctuations in the Burden of Informal Dementia Caregivers, an Experience Sampling Study. info:doi:10.1097/NNR.0000000000000243 info:eu-repo/semantics/altIdentifier/doi/10.1097/NNR.0000000000000243 info:eu-repo/semantics/altIdentifier/pmid/29095373 Pihet, S. Moses Passini, C. Eicher, M. info:eu-repo/semantics/article article 2017 Nursing research, vol. 66, no. 6, pp. 421-431 info:eu-repo/semantics/altIdentifier/eissn/1538-9847 urn:issn:0029-6562 <![CDATA[Informal dementia caregivers (IDCs) are often confronted with important fluctuations in care-related burden, commonly described as "good and bad days." These fluctuations are overlooked by traditional questionnaires focusing on the average experience. The experience sampling method (ESM) is based on the repeated collection of data in everyday life, thereby allowing the description of day-to-day fluctuations in IDC burden, and the identification of their correlates. ESM studies are still scarce among IDCs, with none focusing on day-to-day fluctuations in burden. This ESM study aimed to examine day-to-day fluctuations in the burden of IDCs and test their associations with six moment-to-moment predictors. Primary IDCs (N = 26, median age = 68 years, 77% women, 73% spouses) volunteered to answer questions about their daily burdens, patients' memories and behavioral problems (MBP), caregivers' MBP-related distress, psychological distress, self-efficacy and positive affects, and relationship quality; volunteers did this every evening for 2 weeks on a touchpad, resulting in 206 measures. Data were analyzed with multilevel linear regression. Day-to-day fluctuations covered about two thirds of the total variance for most study variables. All six predictors had a significant bivariate relation with daily burden, explaining 15%-32% of its fluctuations, with significant differences between caregivers in the strength of these relations. The best multivariate model explained 51% of the day-to-day fluctuations in burden. It included caregiver MBP-related distress, psychological distress, and relationship quality. This innovative study of IDC burden shows that day-to-day fluctuations are an important part of caregivers' real-life experiences and that half of this variability is predicted by currently understudied factors. Inviting caregivers to monitor clinical outcomes daily over 1 or 2 weeks could help tailor interventions to their individual needs and also empower them

Development of a rapid and highly sensitive direct-PCR assay to detect a single conidium of Botrytis cinerea Pers.:Fr in vitro and quiescent forms in planta

“Direct-PCR” amplifications of Botrytis cinerea-specific genomic sequences, without any DNA purification step or time consuming sample preparation, were developed. A single copy sequence of 0.7 Kb in the Botrytis cinerea genome was amplified in reactions containing no more than 1 x 105 to 1 single conidium. As a demonstrative application, this assay was applied to detect B. cinerea in different parts of immature grape berries (at ‘pea size’), when previously inoculated with conidia at flowering. Using this method we showed the presence of quiescent Botrytis in the receptacle area only. Cloning and sequencing of the fragment confirmed the single sequence gene of B. cinerea. These results demonstrate that the method is easy to apply and of sufficiently high sensitivity to detect the presence of B. cinerea in immature grape berries. Its use for studies on the development of grey mould and improved control of the disease in vineyards is discussed

Effects of resveratrol, viniferins and pterostilbene on Plasmopara viticola zoospore mobility and disease development

The effects of stilbenes (resveratrol, δ- and ε-viniferins, and pterostilbene) on the mobility of zoospores of Plasmopara viticola and on subsequent disease development were studied in vitro. δ-viniferin and pterostilbene are the most toxic stilbenes concerning zoospore mobility (ED50 : 14.6 and 28.3 μM) and disease development (ED50 : 14.7 and 12.7 μM). The analysis of stilbenes in leaf cells of resistant (Solaris) and susceptible (Chasselas) grape cultivars artificially inoculated with P. viticola has shown that very high amounts of stilbenic phytoalexins accumulate at the site of infection of the resistant cultivar compared to the susceptible one

Magnetic resonance spectroscopy of perpendicularly magnetized permalloy multilayer disks

Using a Magnetic Resonance Force Microscope, we compare the ferromagnetic resonance spectra of individual micron-size disks with identical diameter, 1 $m$m, but different layer structures. For a disk composed of a single 43.3 nm thick permalloy (Py) layer, the lowest energy mode in the perpendicular configuration is the uniform precession. The higher energy modes are standing spin-waves confined along the diameter of the disk. For a Cu(30)/Py(100)/Cu(30) nm multilayer structure, it has been interpreted that the lowest energy mode becomes a precession localized at the Cu/Py interfaces. When the multilayer is changed to Py(100)/Cu(10)/Py(10) nm, this localized mode of the thick layer is coupled to the precession of the thin layer

Electronic control of the spin-wave damping in a magnetic insulator

It is demonstrated that the decay time of spin-wave modes existing in a magnetic insulator can be reduced or enhanced by injecting an in-plane dc current, $I_\text{dc}$, in an adjacent normal metal with strong spin-orbit interaction. The demonstration rests upon the measurement of the ferromagnetic resonance linewidth as a function of $I_\text{dc}$ in a 5~$\mu$m diameter YIG(20nm){\textbar}Pt(7nm) disk using a magnetic resonance force microscope (MRFM). Complete compensation of the damping of the fundamental mode is obtained for a current density of $\sim 3 \cdot 10^{11}\text{A.m}^{-2}$, in agreement with theoretical predictions. At this critical threshold the MRFM detects a small change of static magnetization, a behavior consistent with the onset of an auto-oscillation regime.Comment: 6 pages 4 figure

Histological and biochemical criteria for objective and early selection of grapevine cultivars resistant to Plasmopara viticola

Grapevine breeding is the most effective way to create cultivars resistant to downy mildew (Plasmopara viticola), and to reduce the number of fungicide applications. Four criteria, including histological and biochemical analyses, based on the level of different mechanisms of resistance to grapevine downy mildew, were tested on 42 different cultivars. Plantlets were artificially inoculated with downy mildew and the sporangia density was measured spectrophotometrically 6 d after infection. Callose synthesis in stomata and δ- and ε-viniferin levels at the site of infection were recorded 48 h after inoculation. These observations have allowed the 42 cultivars to be divided into 5 groups: very resistant (VR), resistant (R), less susceptible (LS), susceptible (S) and highly susceptible (HS). All 4 criteria have to be applied to assign the resistance level closer to field conditions. This method allows to rapidly evaluate the level of resistance of seedlings to downy mildew thereby leading to a reduction in duration  of the breeding program by several years.

Two New Primers Highly Specific for the Detection of Botrytis cinerea Pers. Fr.

Of thirty-nine Botrytis cinerea isolates originating in different host-plants and grown in pure cultures, twenty-six produced abundant grey aerial mycelium and sporulated intensely, whilst thirteen produced a thin mycelial layer, abundant sclerotia and secreted an unidentified yellow pigment in PDA culture media. The commonly used C729 +/– primers (5’-AGCTCGAGAGAGATCTCTGA-3’; 5’-CTGCAATGTTCTGCGTGGAA-3’) designed to detect B. cinerea did not amplify the DNA fragment of 0.73 kb in this smaller group of strains under standard conditions, whereas a shorter DNA fragment (0.60 kb) was amplified at a lower annealing temperature (50°C). This fragment was sequenced and two new internal primers were designed, BC108 + (5’-ACCCGCACCTAATTCGTCAAC-3’) and BC563 – (5’-GGGTCTTCGATACGGGAGAA-3’). These new primers were used to amplify a DNA fragment of 0.48 kb for the main group of 26 B. cinerea strains and a shorter fragment (0.36 kb) for the smaller group of 13 strains due to a deletion of 0.12 kb, which was not detected with the primers C729 +/–. All the strains were amplified to detect the presence or absence of Boty and Flipper transposable elements. No correlation was found between strains possessing the deletion and those belonging to either the vacuma or the transposa sibling species. Other closely related Botrytis species such as B. allii and B. fabae were not amplified with these primers, confirming their specificity for B. cinerea and enhancing the sensitivity of the molecular tools available to detect this fungus in host-plants

Fungi from symptomless strawberry plants in Switzerland

Forty symptomless strawberry plants (Fragaria ananassa Duch.) belonging to different cultivars were examined for fungal flora. All the plants had originally been imported as frigo plantlets from the same nursery. Assays were performed on frigo plantlets from one batch and on plants grown under field conditions from another batch. Fungal isolations were taken from different parts of the plants (roots, crowns, petioles, leaves, flowers and fruits). Some 40 different fungal species were isolated in all, about 20 from in frigo plantlets and 30 from field-grown plants (with some overlap). About half the fungi isolated were common fungal strawberry pathogens in Switzerland. This paper outlines the problems inherent in the large-scale import of certified planting material containing potential pathogenic fungi that are not detected by routine phytosanitary inspection

Carbohydrate reserves in grapevine (Vitis vinifera L. 'Chasselas'): the influence of the leaf to fruit ratio

Seasonal dynamics of total non-structural carbohydrates (TNC) in relation to the leaf-fruit ratio were measured over five years at different grapevine phenological stages in one- and two-year-old canes, trunks and roots of the cultivar 'Chasselas' (Vitis vinifera L.). Carbohydrates were mainly stored as starch in different parts of the grapevine during the growing season. Soluble carbohydrates represented only a small part (&lt; 7 % of dry weight, DW) of the TNC. In the roots and trunks, the starch content fluctuated during the growing season, reaching the lowest values between budbreak and flowering depending on the year, and the highest values between harvest and leaf fall. The soluble sugar content increased in the trunks and the two-year-old canes during the winter period with the decrease in temperatures. A negative correlation was established between the average air temperature recorded during the seven days before sample collection for carbohydrate analysis, and soluble carbohydrate content in the trunks and two-year-old canes. The leaffruit ratio (source-sink), expressed by the “light-exposed leaf area∙kg-1 fruit”, not only substantially influenced the soluble sugar content in berries but also the starch and TNC concentrations in the trunks and roots at harvest. Higher leaf-fruit ratios resulted in increased starch and TNC concentrations in the trunks and roots, which attained the maximum values when the leaf-fruit ratio neared 2.0 m2 of light-exposed leaf area∙kg-1 fruit. Canopy height and leaf area had no predominant influence on the soluble sugars, starch contents, or TNC in the permanent vine parts.